Method for preparing sealing composition for storage batteries



Patented Apr. 18, 1950 METHOD FOR PREPARING SEALING COM- POSITION FOR STORAGE BATTERIES Leighton .lohn Thomas, Philadelphia, Pa., assignor to The Electric Storage Battery Company, a corporation of New Jersey No Drawing. Application March 4, 1947,

' Serial No. 732,382

4 Claims. (Cl. 260458) This invention relates to improvements in compositions for sealing storage batteries and methods for preparing the same.

An object of the invention is to. provide improved battery sealing compositions characterized by increased ductility and better adhesive qualitiesthan other battery sealing compositions with which I am familiar.

The present invention is concerned with com positions that contain asphalt and rubber as the principal ingredients. The compositions also may contain additional ingredients to improve the adhesion, such ingredients being resins such as paracumarone-indene or oils such as rosin oil or mineral oil. I am aware that admixtures or blends of asphalt and rubber have foundmany applications in the past. Nevertheless, I have discovered novel methods-of combining these ingredients, either by themselves or with a; resin or an oil, in order to form battery sealing compositions having the improved qualities mentioned.

Accordingly a further object of the invention is to provide improved methods for preparing battery sealing compositions by blending asphalt and rubber, either alone or with a resin or an oil, in the novel manner hereinafter set forth.

The asphalt I prefer to employ is of a grade that alone may be used as a battery sealing compound. It has a melting point within the range 160 to 200 Fahrenheit. Prior to the addition of rubber, the resin or oil may be blended with the asphalt in amounts up to about 20 percent of the total weight (asphalt plus resin or oil). The resin or oil is added directly to the asphalt while the latter is in a molten condition and mixed by any suitable method. When the asphalt contains a sufiicient quantity of the paraffin or mineral oil naturally present, addition of resin or, oil is not necessary. Of the resins or oils that may be added, I prefer rosin oil.

According to the present invention, a quantity of asphalt or asphalt plus resin or oil is melted and heated to a temperature a little above the boiling point of water, preferably about 220 Fahrenheit. Latex containing 30 to 60 percent rubber" solids and the remainder water is added to the molten asphalt. The mixture is agitated and the temperature maintained until substantially all of the water in the latex is'expelled. To assishin the blending a small amount of a wetting agent, of which many are known, may be included in the mixture. Also sulfur may be added as a vulcanizing agent. More asphalt is added after the water is expelled. The resulting: mixture is heated to approximately 409 Fahrenheit for a period of about one hour or longer arid agitated to produce a complete blendingot the ingredients.

The proportions of ingredients employed is such that the final sealing composition contains 1 to 20 percent by weight dry rubber solids. Ap proximately one-third of the -quantity used of asphalt or asphalt plus resin or oil is melted initially and the latex is added thereto. The other two-thirds .of the asphalt is added after the water is expelled from the latex. Sulfur may be added in amounts up to 30 percent of the weight of rubber solids. When sulfur is used, the rubber vulcanizes during heating and the sulfur enters into combination therewith. However, a satisfactory composition is provided irrespective of whether the rubber is vulcanized or u nvulcani zed.

The finished composition consists of the ingredients mentioned in the following ranges by weight:

Percent Asphalt 99 to 60 Resin or oil l 0 to 20 Rubber, based on dry rubber solids 1 to 20 When resin or oil is not used, the minimum content of asphalt is about percent, since it has not been found desirable to employ more than'2'0 percent of rubber.

- The preferred composition consists of these ingredients in the following proportions by weight:

Percent Asphalt About Rosin oil About 10 Rubber, based on dry rubber solids- About 5 Straight asphalt 2.8

Asphalt, percent; rosin oil 10, percent 4.0

Asphalt, 85 percent; rosin oil, 10 percent; rubber, 5 percent, incorporated by the methods described hereinbefore 7.5

A measure of adhesion of battery sealing compositions is furnished by connecting two strips with the compound, applying tension to the joint so formed, and observing whether the joint fails due to the sealing compounds parting from one of the strips or whether the mass of sealing compound breaks "leaving part on each strip. The second manner of failure (referred to as /2 and /2) indicates better adhesion than the first (referred to as 1-0).

Samples A, B and C sealing compositions tested for adhesion in this gave results as follows:

A. (Fresh) aand E. (Fresh) 1/ and "A C. (Fresh) and A; A. (Maintained hot 48 hours) 1-1) B. (Maintained hot 48 hours) and ,6, C. (Maintained hot 48 hours) 'and It is therefore seen that I have provided batitery sealing compositions having improved duetility and adhesion rover battery sealing compo sition's as previously used. a

While I have described :but certain exernpiliazry mmpositions and methods of -preparation, :it is apparent that modifications may arise.

Therefore 'I do vnot *wish to be limited by the disclosure set forth, but only "by the scope of the appended claim.

I claim:

1. A method for preparing batteryisealing compositions comprising the steps of melting and heating asphalt to a temperature above the boiling point of water, adding latex containing 31) to 60 percent 'rubber solids to the molten asphalt, agitating the mixture and maintaining the temperature until the water in the latex is expelled, adding more asphalt, and heating the mixture to a temperature -of about 400 Fahrenheit and continuing the agitation, the initial *quantity 'of asphalt being about one-third of the total thereof and the content -of rubber solids in the (finished composition being from 1 to 20 ;percent.

2. A method for preparing battery-sealing com- ;positions comprising the steps of melting and heating a blend -of asphalt and rosin oil containing 1 to 20 percent by ii'bsin oil to a temperature above the boiling point of water, adding latex containing 30 to 60 percent rubber solids to the molten blend of asphalt and rosin oil. agitating the mixture and maintaining the temperature until the water in the latex is expelled, adding more of the blend of asphzilt rand rosin oil. and heating the mixture to about 400 Fahrenheit and continuing the agitation, the "initial quantity of asphalt and iii:

rosin oihbeing about one-third of the total thereof, and the content of rubber solids in the finished composition being from 1 to 20 percent.

3. a method as set forth in claim 1 including the additional step of vulcanizing the rubber by additions! sulphur in amounts of 1011030 percent rot-the weight olsrubber.

4. A method as set forth in claim 2 including the additional step of 'vu'lcanizing the rubber by addition -=oi sulfur in amounts of "10 "to 30 perce'nt of the weight of rubber.

JGHN

:R'EFFRENCES The 'ioilowin'g references are of -record in the file of this patent:

UNITED STATES BA'IENZI'S 

1. A METHOD FOR PREPARING BATTERY SEALING COMPOSITIONS COMPRISING THE STEPS OF MELTING AND HEATING ASPHALT TO A TEMPERATURE ABOVE THE BOILING POINT OF WATER, ADDING LATEX CONTAINING 30 TO 60 PERCENT RUBBER SOLIDS TO THE MOLTEN ASPHALT, AGITATING THE MIXTURE AND MAINTAINING THE TEMPERATURE UNTIL THE WATER IN THE LATEX IS EXPELLED, ADDING MORE ASPHALT, AND HEATING THE MIXTURE TO A TEMPERATURE OF ABOUT 400* FAHRENHEIT AND CONTINUING THE AGITATION, THE INITIAL QUANTITY OF ASPHALT BEING ABOUT ONE-THIRD OF THE TOTAL THEREOF AND THE CONTENT OF RUBBER SOLIDS IN THE FINISHED COMPOSITION BEING FROM 1 TO 20 PERCENT. 